Disposable lancing device

ABSTRACT

A disposable lancing device including: a lancet housed in a housing and urged by a spring member such that a puncture member provided at a distal end of the lancet is adapted to extend out from the housing so as to carry out a puncturing operation; a locking ring disposed within the housing such that the lancet is allowed to displace in an extension direction through the locking ring; a locking protrusion provided to the lancet and adapted to be engaged by the locking ring so as to hold the lancet in a puncture-ready position located deep in the housing with the spring member being compressed; and an operating member adapted to carry out the puncturing operation by rotating the locking ring so as to disengage the locking protrusion from the locking ring and displace the lancet in the extension direction by means of the spring member.

INCORPORATED BY REFERENCE

The disclosure of Japanese Patent Application No. 2010-141526 filed onJun. 22, 2010 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to a lancing device used tolance or puncture the skin and collect a small quantity of blood, and inparticular to a disposable lancing device intended to be discarded aftera single use.

2. Description of the Related Art

Self-collection of small quantities of blood is sometimes necessary formedical purposes. For example, for patients with diabetes, it isnecessary for the patient himself to regularly collect his own blood inorder to periodically check blood sugar level (Self-Monitoring of BloodGlucose: SMBG). Lancing devices have been in use for some time to enablesuch self-collection of blood to be carried out safely and dependably.In particular, for the purpose of preventing infection, lancing devicesof disposable type designed to be discarded after a single use have beenavailable in the past.

Such lancing devices typically include a lancet housed within a housingand urged by a spring member, and are designed to carry out thepuncturing operation by extending a puncture member provided to thedistal end of the lancet out from the housing. Specifically, asdisclosed in U.S. Publication No. US 2007/0135828, the instrument isdesigned to be used by pushing an operating member with a lancet engagedwithin the housing, so that a spring member disposed deeper than thelancet experiences compressive deformation. When compression force ofthe spring member increases to such an extent as to disengage thelancet, the lancet will extend out from the housing to carry out thepuncturing operation.

However, with the lancing devices of this conventional construction, itis difficult to establish compression force of the spring member that isrequired to disengage the lancet from the housing with sufficientaccuracy. Consequently, there may be a case where, even though thespring member is not sufficiently compressed, the lancet might disengageto induce the puncturing operation, so that insufficient puncturingforce causes shortage of exuded blood. There may be another case, on thecontrary, where even if the operating member is firmly pushed, thelancet might fail to disengage, making it difficult to bring about thepuncturing operation.

International Publication No. WO 2005/110227 and U.S. Pat. No. 5,755,733disclose a structure in which a push operating member that inducescompressive deformation of a spring member is furnished with an abuttingportion for releasing engagement, and when the push operating memberreaches a prescribed position the abutting portion comes into abutmentagainst and disengage a detent piece of a lancet engaged by a housing.However, with such lancing devices, in addition to force for inducingcompressive deformation of the spring member, force for deforming anddisengaging the detent piece of the lancet should be exerted on the pushoperating member, thereby inevitably requiring large operating force.

Meanwhile, U.S. Publication No. US 2007/0225742 and U.S. Publication No.US 2005/0070945 disclose a structure in which a detent piece of a lancetengaged by a housing is designed to be pushed from the horizontaldirection so as to release the engagement, thereby carrying out theextending action. However, since the detent piece of the lancet issubjected to pushing force from the horizontal direction, the centeraxis of the lancet may deviate to catch other components, or the lancetmay be pressed against the other components to increase frictionalresistance during the extending action, posing a risk of impairedmovement of the lancet during the extending action.

Another structure is disclosed in U.S. Pat. No. 7,238,192, in which alancet is rotatable in the circumferential direction with respect to ahousing so that the engagement of the lancet with a seating surfaceformed to the inner face of the housing is adapted to be released byrotating action of the lancet. However, if the lancet is rotated byexerting rotational force, due to deformation or displacement of thelancet there is a risk of difficulty in duly ensuring release of theengagement or stability of the extending action. In particular, with thelancet urged by a spring member, it is difficult to rotate the lancetalone, posing another risk of inducing deformation of the spring memberas well and providing adverse effects on its urging action.

SUMMARY OF THE INVENTION

It is therefore one object of this invention to provide a disposablelancing device of novel construction capable of reliably and stablymaintaining the lance-ready or puncture-ready position where the lancetis engaged in a position to which the spring member is compressed, aswell as carrying out the puncturing operation through disengagement ofthe lancet.

A first mode of the present invention provides a disposable lancingdevice including: a housing; a spring member; a lancet housed in thehousing and urged by the spring member such that a puncture memberprovided at a distal end of the lancet is adapted to extend out from thehousing so as to carry out a puncturing operation; a locking ringdisposed within the housing such that the lancet is allowed to displacein an extension direction through the locking ring; a locking protrusionprovided to the lancet and adapted to be engaged by the locking ring soas to hold the lancet in a puncture-ready position located deep in thehousing with the spring member being compressed; and an operating memberadapted to carry out the puncturing operation by rotating the lockingring so as to disengage the locking protrusion from the locking ring anddisplace the lancet in the extension direction by means of the springmember.

The lancing device according to the present mode employs the lockingring as a separate element from the housing and the lancet. By rotatingthe locking ring, it is possible to disengage the lancet that has beenurged by the spring member while being held in the puncture-readyposition, thereby carrying out the puncturing operation. Thus, thespring member compressed to the puncture-ready position in advance isable to exert a stable urging force on the lancet and bring about thepuncturing operation. In addition, the lancet can avoid being subjectedto the operating force for carrying out the puncturing operation fromthe horizontal direction. Accordingly, catching due to deviation of thecenter axis of the lancet or increase of frictional force against othercomponents will be prevented, thereby realizing the puncturing operationin a stable manner. Moreover, unlike the lancet urged by the springmember, the locking ring to be rotated can be easily rotated alone,making it possible to readily and stably bring about the puncturingoperation.

A second mode of the present invention provides the disposable lancingdevice according to the first mode wherein subsequent to the puncturingoperation, a circumferential position of the locking ring relative tothe lancet is maintained so as to hold the locking protrusion of thelancet disengaged from the locking ring so that the locking protrusionis prevented from being re-engaged by the locking ring.

A third mode of the present invention provides the disposable lancingdevice according to the first or second mode further including areuse-preventing protrusion provided to the lancet and adapted toprevent the locking protrusion from being re-engaged by the locking ringsuch that with the locking ring located at a rotational positionrepresenting that the locking protrusion has been disengaged and thepuncturing operation of the lancet has been carried out, as the lancetis pushed and displaced deep into the housing the reuse-preventingprotrusion comes into abutment against the locking ring so as to limitdeep displacement of the lancet relative to the locking ring.

With the lancing device according to the present mode, areuse-preventing mechanism can be realized by utilizing the lockingring. In particular, in view of the locking ring experiencing rotationaldisplacement during the puncturing operation, the reuse-preventingprotrusions are provided to the lancet so as to come into abutmentagainst the locking ring at its rotational position subsequent to thepuncturing operation. This arrangement makes it possible to realize themechanism for reliably preventing reuse of the instrument with a smallnumber of parts and a simple structure.

A fourth mode of the present invention provides the disposable lancingdevice according to the third mode wherein the locking ring is allowedto displace deep into the housing, and with the locking ring located atthe rotational position representing that the puncturing operation ofthe lancet has been carried out, as the lancet is pushed and displaceddeep into the housing the reuse-preventing protrusion comes intoabutment against the locking ring so that the locking ring experiencesdeep displacement together with the lancet.

With the lancing device according to the present mode, even if it isattempted by pushing the lancet from the distal end side of the housingto forcibly move the locking protrusion of the lancet deeper past thelocking ring and engage it by the locking ring, the locking ring willexperience displacement deeper into the housing together with thelancet, thereby more reliably preventing reuse of the instrument.

A fifth mode of the present invention provides the disposable lancingdevice according to any of the first to fourth modes further includingan inadvertent operation prevention mechanism for inhibiting rotation ofthe locking ring with respect to the housing.

The lancing device according to the present mode is able to prevent anunexpected puncturing operation by inhibiting the locking ring fromrotating. The inhibition of rotation of the locking ring that is noturged in the circumferential direction can easily be realized through acomponent having lower strength compared to the case, for example, whichdirectly inhibits extension of the lancet urged by the spring means.

A sixth mode of the present invention provides the disposable lancingdevice according to the fifth mode further including a cap attached tothe distal end of the lancet so as to cover the puncture member, whereinwith the cap attached, the inadvertent operation prevention mechanism isprovided by the locking ring being engaged nonrotatably with respect tothe housing via either of the cap and the lancet, and through detachmentof the cap the locking ring is adapted to be disengaged to becomerotatable.

In the lancing device according to the present mode, the inadvertentoperation prevention mechanism is designed to be released by means ofthe cap being detached when carrying out the puncturing operation. Thus,it is possible to prevent the inadvertent operation prevention mechanismfrom being improperly released, while allowing the mechanism to bereleased without needing any special operation when carrying out thepuncturing operation.

A seventh mode of the present invention provides the disposable lancingdevice according to any of the first to sixth modes further including aguide mechanism for guiding the lancet in the extension direction whilepreventing circumferential displacement of the lancet with respect tothe housing.

The lancing device according to the present mode is able to surelyprevent interlocked rotation of the lancet in association with rotationof the locking ring, thereby more reliably carrying out the puncturingoperation through rotation of the locking ring. Additionally, stabilityof the puncturing operation through extension of the lancet will be moreimproved.

According to the present invention, by rotating the locking ring, it ispossible to disengage the lancet that has been urged by the springmember while being held in the puncture-ready position, thereby carryingout the puncturing operation. Therefore, the lancet can avoid beingsubjected to the operating force for carrying out the puncturingoperation from the horizontal direction. Accordingly, catching due todeviation of the center axis of the lancet or increase of frictionalforce against other components will be prevented, thereby realizing adesired puncturing operation in a stable manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and/or other objects features and advantages of theinvention will become more apparent from the following description of apreferred embodiment with reference to the accompanying drawings inwhich like reference numerals designate like elements and wherein:

FIG. 1 is a top plane view of a disposable lancing device according to afirst embodiment of the present invention in a standard condition;

FIG. 2 is an exploded perspective view of the lancing device of FIG. 1;

FIG. 3 is a longitudinal sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a longitudinal sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a transverse sectional view taken along line 5-5 of FIG. 3;

FIG. 6 is a fragmentary enlarged view of FIG. 2;

FIG. 7 is a perspective view of a locking ring of the lancing device ofFIG. 1;

FIG. 8 is a rear view suitable for explaining action of the locking ringin the standard condition shown in FIG. 1 or in a puncture-readycondition;

FIG. 9 is a front view suitable for explaining action of the lockingring in the standard condition shown in FIG. 1 or in the puncture-readycondition;

FIG. 10 is a longitudinal sectional view showing the puncture-readycondition of the lancing device of FIG. 1, corresponding to FIG. 3;

FIG. 11 is a longitudinal sectional view taken along line 11-11 of FIG.10;

FIG. 12 is a transverse sectional view suitable for explaining apuncturing operation of the lancing device of FIG. 1, corresponding toFIG. 5;

FIG. 13 is a rear view suitable for explaining action of the lockingring in the puncturing operation condition shown in FIG. 12 and in apost-puncture condition;

FIG. 14 is a front view suitable for explaining action of the lockingring in the puncturing operation condition shown in FIG. 12 and in thepost-puncture condition;

FIG. 15 is a longitudinal sectional view showing the puncturingoperation condition of the lancing device of FIG. 1, corresponding toFIG. 3;

FIG. 16 is a longitudinal sectional view taken along line 16-16 of FIG.15;

FIG. 17 is a longitudinal sectional view showing the post-puncturecondition of the lancing device of FIG. 1, corresponding to FIG. 3;

FIG. 18 is a longitudinal sectional view taken along line 18-18 of FIG.17;

FIG. 19 is a longitudinal sectional view suitable for explaining apreventing operation of reuse of the lancing device of FIG. 1,corresponding to FIG. 3;

FIG. 20 is a longitudinal sectional view taken along line 20-20 of FIG.19;

FIG. 21 is a longitudinal sectional view of a disposable lancing deviceaccording to a second embodiment of the present invention in a standardcondition;

FIG. 22 is a longitudinal sectional view taken along line 22-22 of FIG.21;

FIG. 23 is a transverse sectional view taken along line 23-23 of FIG.21;

FIG. 24 is an exploded perspective view of the lancing device of FIG.21;

FIG. 25 is a rear view suitable for explaining action of a locking ringin the standard condition shown in FIG. 21 or in a puncture-readycondition;

FIG. 26 is a rear perspective view suitable for explaining action of thelocking ring, when the lancing device of FIG. 21 is in thepuncture-ready condition;

FIG. 27 is a longitudinal sectional view showing the puncture-readycondition of the lancing device of FIG. 21, corresponding to FIG. 21;

FIG. 28 is a transverse sectional view suitable for explaining apuncturing operation of the lancing device of FIG. 21, corresponding toFIG. 23;

FIG. 29 is a rear view suitable for explaining action of the lockingring in the puncturing operation condition shown in FIG. 28 or in apost-puncture condition;

FIG. 30 is a rear perspective view suitable for explaining action of thelocking ring in the puncturing operation condition shown in FIG. 28;

FIG. 31 is a longitudinal sectional view showing the puncturingoperation condition of the lancing device of FIG. 21, corresponding toFIG. 21;

FIG. 32 is a longitudinal sectional view showing the post-puncturecondition of the lancing device of FIG. 21, corresponding to FIG. 21;

FIG. 33 is a longitudinal sectional view suitable for explaining apreventing operation of reuse of the lancing device of FIG. 21,corresponding to FIG. 21; and

FIG. 34 is a longitudinal sectional view taken along line 34-34 of FIG.33;

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

First, FIG. 1 depicts in plan view a disposable lancing device 10according to a first embodiment of the present invention, while FIGS. 2to 5 depict the instrument in exploded perspective view, longitudinalsectional view, and transverse sectional view. FIGS. 1, 3, 4, and 5 alldepict the lancing device 10 in the retail product condition (standardcondition) in which it is provided to the user. The lancing device 10includes a lancet 14 and a compression coil spring (serving as a springmember) 16 housed in a housing 12, and is designed to be used byremoving a needle cap 18 (serving as a cap) from the lancet 14 and thenextending the lancet 14 out from the housing 12 through push operationof an operating element 20, to carry out the lancing or puncturingoperation. Unless indicated otherwise, in the following description,center axis direction refers to the center axis direction of the housing12 and the lancet 14 (the horizontal direction in FIG. 1); the leftwarddirection in FIG. 1, which represents the extension direction of thelancet 14, refers to the front; and the rightward direction refers tothe back.

Turning to a more detailed description, the housing 12 is composed of ahousing main body 22 and a housing nose cone 24 each molded from resin.The housing main body 22 has a deep, generally bottomed cylindricalshape, to the mouth of which fixedly attached the housing nose cone 24,which has generally cylindrical shape.

A spring seat 26 is disposed on the basal wall of the housing main body22 and projects inward from the center of its inside face. A pluralityof guide ribs 28 extend in straight lines in the axial direction andprotrude up from the inside peripheral face of the cylinder wall of thehousing main body 22. The plurality of guide ribs 28 define a pair ofguide rails 30, 30 which are situated in opposition in theaxis-perpendicular direction on the cylinder wall inside face of thehousing main body 22.

The operating element 20 provided as the operating member is formed onthe cylinder wall of the housing main body 22 at a location near themouth section, which is slightly flared relative to the basal wallsection. This operating element 20 is arranged within a passage window34 formed in the peripheral wall of the housing main body 22, and ispartially connected to the housing main body 22. When the operatingelement 20 is pushed with the finger from outside the housing main body22, the connecting portion experiences elastic deformation so that theoperating element 20 is displaced inwardly towards the housing main body22.

An interlock rib 36 that protrudes up from the outside peripheral faceand extends in the circumferential direction is integrally formed at thelip of the mouth of the cylindrical wall of the housing main body 22.Meanwhile, a large-diameter interlock ring 38 extending in thecircumferential direction about the outside perimeter is integrallyformed at the axial back end of the housing nose cone 24. The interlockring 38 is connected to and supported on the housing nose cone 24through connecting leg portions 40 that protrude out at severallocations along the circumference of the outside peripheral face of thehousing nose cone 24.

The housing nose cone 24 is installed on the housing main body 22 byattaching the housing nose cone 24 to the mouth of the housing main body22 and interlocking the interlock rib 36 of the housing main body 22 inthe interlock ring 38 of the housing nose cone 24. In the assembledstate, the interlocking action of the interlock rib 36 with respect tothe interlock ring 38 serves to securely position the housing nose cone24 in the axial direction with respect to the housing main body 22,while the interlocking action of the interlock rib 36 with respect tothe connecting leg portions 40 serves to securely position the housingnose cone 24 in the circumferential direction with respect to thehousing main body 22.

The housing nose cone 24 extends rearward with cylindrical contoursalong the center axis to meet the inside peripheral side of theinterlock ring 38, thereby defining a support cylinder portion 42adapted for insertion into the housing main body 22. The connecting legportions 40 which protrude up from the outside peripheral face of thehousing nose cone 24 extend for prescribed distance in the axialdirection until reaching the outside peripheral face of the supportcylinder portion 42. A pair of cap locking projections 47, 47 formed onthe inside peripheral face of the housing nose cone 24 protrude out atlocations situated in opposition in the axis-perpendicular direction inproximity to the front opening.

A pair of first guide slots 44, 44 and a pair of second guide slots 46,46 are formed extending parallel to the axial direction at locations inrespectively situated in opposition in the diametrical direction on theinside peripheral face of the housing nose cone 24. Each of these firstguide slots 44, 44 and second guide slots 46, 46 extends from theaxially medial section of the housing nose cone 24 to the insideperipheral face of the support cylinder portion 42, and opens onto theback end of the support cylinder portion 42.

In the present embodiment in particular, the diametrical direction ofopposition of the pair of first guide slots 44, 44 and the diametricaldirection of opposition of the pair of second guide slots 46, 46 areorthogonal to one another. The first guide slots 44 have greater widthdimension in the circumferential direction and greater depth dimensionin the diametrical direction than do the second guide slots 46, and inthe support cylinder portion 42 take the form of slits passing throughthe peripheral wall of the support cylinder portion 42.

The lancet 14 is assembled together with the housing 12 composed of thehousing main body 22 and the housing nose cone 24 so as to beaccommodated in the interior space thereof. The housing nose cone 24 ispreferably transparent or translucent so that the collected blood isvisible subsequent to puncture.

The lancet 14 is an insertion-molded component composed of a punctureneedle 52 (serving as a puncture member) embedded and anchored in a rodshaped lancet hub 50 of made of synthetic resin, and extending along thecenter axis. The tip of the puncture needle 52 projects in the forwarddirection from the center of the distal end portion of the lancet hub50.

A spring seat 54 furnished with an annular support protruding portionthat extends in the circumferential direction is formed at the back endof the lancet hub 50. A pair of guide protrusions 56, 56 are integrallyformed on the outside peripheral face of the back end section of thelancet hub 50 and protrude out to either side in the axis-perpendiculardirection. Meanwhile, a pair of reuse-preventing protrusions 58, 58 areintegrally formed on the outside peripheral face of the front endsection of the lancet hub 50 and protrude out to either side in theaxis-perpendicular direction. A pair of locking protrusions 60, 60 areintegrally formed on the outside peripheral face of the lancet hub 50 atlocations axially rearward by a prescribed dimension from the pair ofreuse-preventing protrusions 58, 58, and protrude out to either side inthe axis-perpendicular direction.

The direction of protrusion of the pair of reuse-preventing protrusions58, 58 and the direction of protrusion of the pair of lockingprotrusions 60, 60 differ from one another. In the present embodiment inparticular, the direction of protrusion of the pair of reuse-preventingprotrusions 58, 58 and the direction of protrusion of the pair oflocking protrusions 60, 60 differ from one another by 90 degrees aboutthe center axis, while the direction of protrusion of the pair ofreuse-preventing protrusions 58, 58 and the direction of protrusion ofthe pair of guide protrusions 56, 56 are the same about the center axis.

A needle cap 18 is provided to the distal end side of the lancet hub 50.The integrally formed needle cap 18 is rod-shaped and extends from thedistal end of the lancet hub 50 from which the puncture needle 52projects, along the same center axis. A twist-off portion 64 constrictedto smaller outside diameter defines the boundary section of the lancethub 50 and the needle cap 18, and is designed so that the needle cap 18can be detached from the lancet hub 50 by a manual operation involvingtwisting the needle cap 18 about the center axis relative to the lancethub 50 to induce separation at the twist-off portion 64. By detachingthe needle cap 18 from the lancet hub 50, the distal end part of thepuncture needle 52 that was covered by the needle cap 18 is now exposed.

As depicted in FIG. 6, the distal end part of the needle cap 18 takesthe form of a flattened grip portion 66; in sections to either side inthe width direction of rear end section of this grip portion 66,protrusions 68 and a tongue-shaped elastic catch portions 70 are formedprotruding out at locations situated in opposition in the axialdirection.

The lancet 14 is inserted into the housing main body 22 from the backend of the lancet hub 50, and is assembled arranged on the center axisof the housing 12, with the needle cap 18 passing through the housingnose cone 24. During assembly of the lancet 14 with the housing 12, thecompression coil spring 16 and a locking ring 72 are installed withinthe housing 12 as well.

Specifically, the compression coil spring 16 is accommodated within thebasal portion of the housing main body 22 and arranged on the centeraxis with the back end portion thereof positioned fitting within thespring seat 26 of the housing main body 22, and with the front endportion mated with the spring seat 54 of the lancet hub 50. Thecompression coil spring 16 is thereby interposed between the axiallyopposed faces of the basal portion of the housing main body 22 and theback end of the lancet hub 50, and through displacement of the lancethub 50 rearward in the axial direction (deeper into the housing mainbody 22) is induced to undergo compressive deformation, the urging forceassociated with this compressive deformation being exerted in thedirection pushing the lancet hub 50 forward and out from the housingmain body 22.

Meanwhile, as depicted in FIGS. 6 to 9, the locking ring 72 is a moldedresin component of generally circular ring shape rotatably attachedabout the outside of the support cylinder portion 42 of the housing nosecone 24. A pair of abutting leg portions 74, 74 integrally formed on thelocking ring 72 protrude in the forward direction, and these abuttingleg portions 74, 74 insert between adjacent connecting leg portions 40,40 along the circumference of the support cylinder portion 42. When thelocking ring 72 is then rotated, the abutting leg portions 74 come intoabutment against the connecting leg portions 40 in the circumferentialdirection, thereby limiting the permissible range of rotation of thelocking ring 72 on the support cylinder portion 42 to less than 45degrees.

An integrally formed mating portion 75 of inner flange shape is situatedat the back end part of the locking ring 72; a pair of first passageslots 76, 76 and a pair of second passage slots 78, 78 are formed on theinside peripheral face of this mating portion 75 and extend parallel tothe axial direction at locations respectively situated in opposition inthe diametrical direction. These first passage slots 76, 76 and secondpassage slots 78, 78 each extend in a straight line along the entireaxial length of the mating portion 75.

The inside diameter dimension of the mating portion 75 is slightlylarger than the outside diameter dimension of the lancet hub 50 and theneedle cap 18, and the locking ring 72 is installed fitting about theoutside of the lancet hub 50 and the needle cap 18. The first passageslots 76 of the mating portion 75 have slightly larger cross sectionthan the reuse-preventing protrusions 58 of the lancet hub 50, making itpossible for the reuse-preventing protrusions 58 to travel in the axialdirection through the first passage slots 76. The second passage slots78 of the mating portion 75 have slightly larger cross section than thelocking protrusions 60 of the lancet hub 50, making it possible for thelocking protrusions 60 to travel in the axial direction through thesecond passage slots 78.

The angle (intersection angle) formed by the diametrical direction ofopposition of the pair of first passage slots 76, 76 and the diametricaldirection of opposition of the pair of second passage slots 78, 78 inthe locking ring 72 differs from the angle (intersection angle) formedby the diametrical direction of opposition of the pair ofreuse-preventing protrusions 58, 58 and the diametrical direction ofopposition of the pair of locking protrusions 60, 60 on the lancet hub50. In the present embodiment in particular, the diametrical directionof opposition of the pair of first passage slots 76, 76 and thediametrical direction of opposition of the pair of second passage slots78, 78 intersect one another at approximately 60 degrees.

As will be apparent from FIGS. 8 and 9, according to this arrangement,with the lancet hub 50 passed through the locking ring 72 and the pairof reuse-preventing protrusions 58, 58 of the lancet hub 50 positionedat relative locations in the circumferential direction aligned with thepair of first passage slots 76, 76 of the locking ring 72 so as topermit passage thereof in the axial direction, the pair of lockingprotrusions 60, 60 of the lancet hub 50 are positioned offset from thepair of second passage slots 78, 78 of the locking ring 72, whereby thelocking protrusions 60, 60 are detained by the locking ring 72 andprevented from traveling forward in the axial direction. On the otherhand, with the pair of locking protrusions 60, 60 of the lancet hub 50aligned with the pair of second passage slots 78, 78 of the locking ring72 so as to permit passage thereof in the axial direction, the pair ofreuse-preventing protrusions 58, 58 of the lancet hub 50 are positionedoffset from the pair of first passage slots 76, 76 of the locking ring72, whereby the reuse-preventing protrusions 58, 58 are detained by thelocking ring 72 and prevented from traveling towards the axial rear ofthe lancet hub 50 relative to the locking ring 72.

The pair of reuse-preventing protrusions 58, 58 and the pair of lockingprotrusions 60, 60 of the lancet hub 50 are separated by a distanceslightly greater than the thickness dimension of the mating portion 75of the locking ring 72 in the direction of the center axis. Thus, withthe reuse-preventing protrusions 58, 58 positioned axially forward andaway from the mating portion 75 and the locking protrusions 60positioned axially rearward and away from the mating portion 75, thelocking ring 72 fitting about the outside of the lancet hub 50 is ableto rotate relative to the lancet hub 50. By rotating the locking ring72, either the pair of reuse-preventing protrusions 58, 58 or the pairof locking protrusions 60, 60 are selectively aligned with the firstpassage slots 76, 76 or the second passage slots 78, 78 so as to allowdisplacement therethrough in the axial direction.

A pair of presser tabs 80, 80 are integrally formed on the outsideperipheral surface of the locking ring 72 and protrude out to eitherside in the diametrical direction. The presser tabs 80 are shaped likescalene right triangles when viewed in the axial direction of thelocking ring 72; the face corresponding to the diagonal face thereofconstitutes a sloped pressing face 82 that is inclined about the centeraxis of the locking ring 72. As depicted in FIGS. 3 and 5, with thelocking ring 72 installed on the support cylinder portion 42 thesepresser tabs 80, 80 align so as to be positioned inwardly from theoperating element 20 of the housing main body 22.

The lancing device 10 of the present embodiment is assembled byinstalling the lancet 14, together with the compression coil spring 16and the locking ring 72, within the housing 12 in the above manner. Theguide protrusions 56, 56 that protrude from the lancet hub 50 areinserted through the guide rails 30, 30 provided as a guide mechanismfor guiding the lancet 14 in the direction of extension, allowing thelancet 14 installed within the housing 12 to move in the axial directionwhile preventing rotation of the lancet 14 about the center axis, i.e.circumferential displacement relative to the housing 12.

As depicted in FIG. 4, in the standard condition in which the instrumentis provided as a retail product to the user, the cap locking projections47, 47 of the housing nose cone 24 are respectively locked in place bybeing clasped axially between the protrusions 68 and elastic catchportions 70 formed on the needle cap 18, positioning the lancet 14 inthe axial direction with respect to the housing 12 so that the gripportion 66 of the needle cap 18 projects a prescribed distance to theoutside from the housing nose cone 24.

As depicted in FIG. 3, in this standard condition, the lancet 14 ispushed deeper into the housing main body 22, inducing compressivedeformation of the compression coil spring 16 until the lockingprotrusions 60, 60 of the lancet hub 50 are positioned to the back ofthe locking ring 72. As depicted in FIG. 4, in this condition, thereuse-preventing protrusions 58, 58 of the lancet hub 50 are positionedstraddling across the first passage slots 76, 76 of the locking ring 72and the first guide slots 44, 44 of the support cylinder portion 42 ofthe housing nose cone 24. That is, this engagement of thereuse-preventing protrusions 58 within the first passage slots 76 of thelocking ring 72 and the first guide slots 44 of the housing nose cone 24constitutes an inadvertent operation prevention mechanism designed tolock the locking ring 72 nonrotatably in the circumferential directionrelative to the housing nose cone 24.

As depicted in FIG. 5, in this positioned condition, the sloped pressingface 82 of the presser tab 80 of the locking ring 72 is positioned inopposition inwardly from the operating element 20. When the operatingelement 20 is then pushed into the housing 12 with the finger, onecircumferential end of the operating element 20 presses against thesloped pressing face 82, and on the basis of component force actionproduced according to the slope angle of the sloped pressing face 82,the pushing force of the operating element 20 is converted to rotationalforce that is exerted on the locking ring 72. As mentioned earlier, inthe standard condition depicted in FIGS. 3 and 4, rotation of thelocking ring 72 relative to the housing 12 is prevented, and thusinadvertent actuation of the puncturing operation of the lancing device10 is avoided even if the operating element 20 is accidentally pressed.

(Puncture-ready Condition)

The description now turns to a discussion of the puncturing operationusing the lancing device 10 provided in the standard condition discussedabove. First, with the lancing device 10 in the standard conditiondepicted in FIGS. 3 and 4, the housing 12 is grasped in one hand whilethe other hand grasps the needle cap 18 and twists the needle cap 18.This causes the protrusions 68 and the elastic catch portions 70 of theneedle cap 18 to disengage from the cap locking projections 47 of thehousing nose cone 24, and the needle cap 18 to twist off from the lancethub 50 at the twist-off portion 64 so that the needle cap 18 detachesfrom the housing nose cone 24. Through this operation, the lancingdevice 10 is brought from the standard condition to the puncture-readycondition depicted in FIGS. 10 and 11.

With the lancing device 10 in this puncture-ready condition, the needlecap 18 is released from being positioned in the axial direction withrespect to the housing nose cone 24, and the lancet hub 50 moves axiallyforward under the urging force of the compression coil spring 16. Thelocking protrusions 60 of the lancet hub 50 come into abutment againstthe back end face of the mating portion 75 of the locking ring 72,preventing displacement further forward in the axial direction. Thislocking action of the locking protrusions 60 against the locking ring 72maintains the lancet 14 in the puncture-ready position.

As the lancet hub 50 moves into this position, the reuse-preventingprotrusions 58, 58 of the lancet hub 50 move away in the forwarddirection from their position of engagement in the first passage slots76, 76 of the locking ring 72, and become positioned so as to be engagedexclusively in the first guide slots 44, 44 of the housing nose cone 24.

Thus, in the puncture-ready condition, the reuse-preventing protrusions58, 58 and the locking protrusions 60, 60 of the lancet hub 50 disengageto the axially forward side and rearward side, respectively, of thefirst passage slots 76, 76 and the second passage slots 78, 78 of thelocking ring 72, thereby allowing the locking ring 72 to rotate insidethe housing 12.

(Puncturing Operation Condition)

Accordingly, to bring the instrument from the puncture-ready conditionto the puncturing operation condition for the puncturing operation totake place, as depicted in FIG. 12, the operating element 20 is pushedwith the finger while holding the lancing device 10 in thepuncture-ready condition. By pressing in the operating element 20against the sloped pressing face 82 of the locking ring 72, the lockingring 72 rotates about the center axis with respect to the housing 12 andthe lancet 14. As depicted in FIGS. 13 and 14, when the second passageslots 78, 78 of the locking ring 72 align with the locking protrusions60, 60 of the lancet hub 50 that were previously abutting the back endface of the locking ring 72, the locking protrusions 60, 60 are releasedfrom the condition of inhibited displacement in the axial direction bythe locking ring 72, thereby allowing displacement of the lockingprotrusions 60, 60 in the axially forward direction through the secondpassage slots 78, 78 of the locking ring 72.

As a result, as depicted in FIGS. 15 and 16, the lancet 14 travelsaxially forward inside the housing 12 in a forceful manner under theurging force of the compression coil spring 16. The lancet 14 therebytravels axially forward until the guide protrusions 56, 56 of the lancet14 come into abutment against the back end face of the locking ring 72,whereby the tip of the puncture needle 52 of the lancet 14 extends aprescribed distance outward from the front end opening of the housingnose cone 24 so that the puncturing operation may take place.

(Post-puncture)

During the puncturing operation, owing to the urging force of thecompression coil spring 16, the lancet 14 travels axially forward by adistance exceeding the free length of the compression coil spring 16. Atthis point, because the axial ends of the compression coil spring 16 arerespectively anchored to the basal part of the housing main body 22 andthe back end part of the lancet 14, at the moment of puncture at whichthe puncture needle 52 extends out from the housing nose cone 24, therestoring force of the compression coil spring 16 acts on the lancet 14in the direction drawing back inside the housing 12.

As a result, the puncturing operation of the puncture needle 52extending out from the housing nose cone 24 takes place instantaneously,and subsequent to puncture the lancet 14 is rapidly withdrawn backinside the housing 12 and the tip of the puncture needle 52 is keptinside the housing nose cone 24, as depicted in FIGS. 17 and 18.

(Prevention of Reuse)

Subsequent to the puncturing operation described above, as depicted inFIGS. 17 and 18, the lancet 14 is retained at an axial location that isdetermined by the free length of the compression coil spring 16. Thelocking ring 72 that was previously rotated by the operating element 20remains at its position subsequent to rotation as depicted in FIGS. 13and 14. Specifically, subsequent to puncture, the locking ring 72 isheld at a rotational position representing the unlocked state with norotational force being exerted upon it, so even if the lancet 14 ispushed inward the locking protrusions 60 simply travel through thesecond passage slots 78 so that the locking protrusions 60 are notdetained by the locking ring 72. Thus, subsequent to puncture, thepuncturing operation to extend the lancet 14 axially forward cannot bereproduced even if the operating element 20 is operated.

Additionally, if subsequent to puncture it is attempted to forciblyreuse the instrument by pushing a piece of wire or the like through thefront opening of the housing 12 to push the lancet 14 deep into thehousing 12, as depicted in FIGS. 13 and 14, because the relativepositions in the circumferential direction of the reuse-preventingprotrusions 58, 58 and the locking protrusions 60, 60 of the lancet 14differ from the relative positions in the circumferential direction ofthe first passage slots 76, 76 and the second passage slots 78, 78 ofthe locking ring 72, attempts at reuse can be dependably defeated.

Specifically, when the lancet 14 is forcibly pushed deeper into thehousing 12, even if the locking protrusions 60, 60 of the lancet 14 canbe successfully aligned with the second passage slots 78, 78 in thecircumferential direction so that the locking protrusions 60, 60 movedeeper past the locking ring 72, at this point in time thereuse-preventing protrusions 58, 58 have already been positioned out ofalignment with respect to the first passage slots 76, 76. Thus, as shownin FIGS. 19 and 20, as the lancet 14 is pushed deeper in, thereuse-preventing protrusions 58, 58 come into abutment against the frontend face of the mating portion 75 of the locking ring 72 so that thelocking ring 72 simply moves deeper into the housing 12 together withthe lancet 14, making it substantially impossible for lancet 14 to bere-engaged by the locking ring 72 to bring about the puncture-readycondition depicted in FIGS. 8 to 11.

In the present embodiment in particular, the locking ring 72 ispositioned to the back of the housing nose cone 24, and is larger indiameter than the support cylinder portion 42 of the housing nose cone24 and positioned slipped about the outside of the support cylinderportion 42. Thus, the locking ring 72 is substantially concealed fromview even if one looks in through the front opening of the housing nosecone 24, thus making it substantially impossible to bring aboutrotational displacement of the locking ring 72 while simultaneouslypushing the lancet 14 inward through the small front opening of thehousing nose cone 24.

Additionally, through the engaging action of the guide protrusions 56,56 in the guide rails 30, 30 the lancet 14 is prevented from rotatingabout the center axis relative to the housing 12, so relative rotatingaction cannot be exerted on the locking ring 72 by rotating the lancet14. Moreover, as noted previously, because the locking ring 72 isallowed to travel deeper into the housing main body 22, if it isattempted to rotate the locking ring 72 using a piece of wire or thelike inserted through the front opening of the housing nose cone 24, itwill be exceedingly difficult for the wire etc. to produce contactreaction force of the locking ring 72 in the axial direction.

While one preferred embodiment of the invention has been described indetail herein, it is to be understood that the invention should in noway be limited by the details of the illustrated embodiment. Forexample, FIGS. 21 to 34 illustrate a disposable lancing device 100according to a second embodiment of the present invention, which employsa locking ring 72 having another construction. In the disposable lancingdevice 100 of the present embodiment, elements like those in the firstembodiment shall be designated by like reference numerals and will notbe discussed in detail.

FIG. 24 depicts the lancing device 100 of the present embodiment inexploded view and FIGS. 21 to 23 depict the lancing device 100 in thestandard condition, namely, the retail product condition in which it isprovided to the user. As seen in the drawings, in comparison with thefirst embodiment, the lancing device 100 is not equipped with the pairof reuse-preventing protrusions (58, 58) that protrude up from thelancet hub 50. In the present embodiment, a pair of rotation inhibitingprotrusions 102, 102 are formed at approximately the same locations asthe pair of reuse-preventing protrusions (58, 58) of the firstembodiment.

In association therewith, the contour of the mating portion 75 of thelocking ring 72 differs from that of the first embodiment. Specifically,the mating portion 75 of inner flange shape is furnished with a pair ofnotches 104, 104 situated in opposition in the diametrical direction andeach traversing about one fourth of its periphery. Further, thethickness of the back end face of the mating portion 75 of the lockingring 72 is partially reduced so as to define a pair of thinned portions106, 106 which are situated in opposition in the diametrical direction.By so doing, pressing faces 82 are defined by the shoulder faces locatedat the border of the thinned portions 106 and positioned on the back endface of the mating portion 75 of the locking ring 72. That is, thepresser tabs 80, 80 in the first embodiment that protrude from theoutside peripheral face of the locking ring 72 are replaced by thethinned portions 106, 106 in the present embodiment. By means of thepressing face 82 defined by the shoulder face located at the border ofthe thinned portion 106, component force of the pushing force of theoperating element 20 provided to the housing 12 will be exerted on thelocking ring 72 and serve as rotational force.

In the standard condition depicted in FIGS. 21 to 23 in which the lancet14 is positioned in the axial direction with respect to the housing 12by engaging the needle cap 18 within the housing nose cone 24, thelocking protrusions 60 are positioned axially rearward and away from theback end face of the mating portion 75 while the rotation inhibitingprotrusions 102, 102 are positioned within the mating portions 75, 75 asshown in FIG. 25. In this state, both circumferential end portions ofthe each rotation inhibiting protrusion 102 are situated in oppositionto the circumferential end portion of the each notch 104 about thecenter axis. With this arrangement, when the locking ring 72 rotatesabout the center axis, the rotation inhibiting protrusion 102 of thelancet 14 comes into abutment against the notch 104 of the matingportion 75. In addition, the lancet 14 is prevented from rotating aboutthe center axis through insertion of its guide protrusions 56, 56 intothe guide rails 30, 30 of the housing main body 22. Accordingly, in thestandard condition, an inadvertent operation prevention mechanism, inwhich the rotation inhibiting protrusions 102, 102 come into abutmentagainst the notches 104, 104 and the guide protrusions 56, 56 areinserted into the guide rails 30, 30 so as to be prevented from rotatingabout the center axis, prevents rotation of the locking ring 72 throughengaging action of the locking ring 72 in the housing 12 via the lancet14.

The description now turns to a discussion of the puncturing operationusing the lancing device 100 provided in the standard conditiondiscussed above. First, as in the first embodiment, the needle cap 18 istwisted off from the lancet hub 50 so that the needle cap 18 detachesfrom the housing nose cone 24 to bring the instrument to thepuncture-ready condition as depicted in FIGS. 26 and 27. With thelancing device 100 in this puncture-ready condition, as in the firstembodiment, the lancet hub 50 is released from being positioned by theneedle cap 18 in the axial direction, and the lancet hub 50 movesaxially forward under the urging force of the compression coil spring16. Consequently, the locking protrusions 60, 60 of the lancet hub 50come into abutment against the back end face of the mating portion 75 ofthe locking ring 72.

As the lancet hub 50 moves into this position, the rotation inhibitingprotrusions 102, 102 of the lancet hub 50 move away in the forwarddirection from the mating portion 75 of the locking ring 72, therebyallowing the locking ring 72 to rotate inside the housing 12.

Accordingly, in this puncture-ready condition, similar to the firstembodiment, as the operating element 20 is pushed inwardly towards thehousing 12, the operating element 20 is pressed against the pressingface 82 of the locking ring 72, so that the locking ring 72 rotatesabout the center axis with respect to the housing 12 and the lancet 14under the component force in the rotational direction. By so doing, asdepicted in FIGS. 28 to 30, when the locking protrusions 60, 60 of thelancet hub 50 that were previously abutting the back end face of themating portion 75 of the locking ring 72 align with the notches 104, 104of the locking ring 72, the lancet hub 50 is released from the conditionof inhibited displacement in the axial direction, thereby allowingdisplacement of the locking protrusions 60, 60 in the axially forwarddirection through the notches 104, 104 of the locking ring 72.

As a result, as depicted in FIG. 31, the lancet 14 travels axiallyforward inside the housing 12 in a forceful manner under the urgingforce of the compression coil spring 16. As in the first embodiment, thepuncture needle 52 extends instantaneously out of the front opening ofthe housing 12 so that the puncturing operation may take place. In thepresent embodiment, a plurality of positioning ribs 108 protrude fromthe inside peripheral face of the tubular portion of the housing mainbody 22 so as to extend in the axial direction over the basal end sidethereof in which the compression coil spring 16 is disposed. Owing tothese plurality of positioning ribs 108, the compression coil spring 16is able to be stably positioned along the center axis and undergoextensional and contractive deformation.

Moreover, as illustrated in FIG. 32, in the post-puncture condition inwhich the tip of the puncture needle 52 is kept inside the housing nosecone 24, the locking ring 72 that was previously rotated by theoperating element 20 remains at its position subsequent to rotation asdepicted in FIGS. 29 and 30. Thus, subsequent to puncture, even if it isattempted to forcibly reuse the instrument by pushing the lancet 14 deepinto the housing 12, as depicted in FIGS. 33 and 34, the lockingprotrusions 60, 60 of the lancet 14 simply moves deeper into the housingmain body 22 through the notches 104, 104 of the locking ring 72, makingit substantially impossible for lancet 14 to be re-engaged by thelocking ring 72 to bring about the puncture-ready condition depicted inFIGS. 25 to 27.

In the present embodiment in particular, because the guide protrusions56, 56 are inserted into the guide rails 30, 30 so as to prevent thelancet 14 from rotating about the center axis with respect to thehousing 12, it is also impossible for the lancet 14, which has beenpushed in, to be rotated and engaged by the locking ring 72. Therefore,in order to bring about the puncture-ready condition again subsequent topuncture, it is necessary to induce rotational displacement of thelocking ring 72 while simultaneously pushing the lancet 14 inwardthrough the small front opening of the housing nose cone 24.Accordingly, it will be even more difficult to reuse the instrument.

In the lancing devices 10, 100 according to the preceding first andsecond embodiments, a single compression coil spring 16 is disposedwithin the housing 12 and adapted to exert both extending force andwithdrawing-back force on the lancet 14. However, it would alternativelybe acceptable for example to provide the lancet 14 with a spring memberfor exerting urging force in the extension direction and a spring memberfor exerting urging force in the withdrawing-back direction separately.

Also, with regard to the puncture member, the puncture needle 52 asshown by way of example herein may be replaced by a blade or the like.

Furthermore, in the first and second embodiments the inadvertentoperation prevention mechanism which prevents the locking ring 72 fromrotating with respect to the housing 12 is employed in order to preventundesired extending action of the lancet 14 in the standard condition.However, it could instead be possible to employ an inadvertent operationprevention mechanism which is, for example, inserted within theoperating element 20 and prevents displacement of the operating element20 per se in the pushing direction towards the housing 12.

Moreover, in the preceding embodiments, the lancet 14 is engaged by thelocking ring 72 with either the reuse-preventing protrusions 58 or therotation inhibiting protrusions 102 while being engaged by the housing12 with the guide protrusions 56 so as to lock the locking ring 72nonrotatably with respect to the housing 12, thereby providing theinadvertent operation prevention mechanism. However, instead ofemploying the lancet 14 of this construction, it would also beacceptable to employ a cap 18 that is furnished with eitherreuse-preventing protrusions or rotation inhibiting protrusions adaptedto be engaged by the locking ring 72 while being furnished with guideprotrusions adapted to be engaged by the cap locking projections 47 soas to lock the locking ring 72 nonrotatably with respect to the housing12, thereby providing an inadvertent operation prevention mechanism.

In addition, in order to prevent the locking ring 72 from inadvertentlydetaching from the housing nose cone 24 and moving axially rearwardduring the standard condition or puncture-ready condition, a protrudingpart may be provided to the inner face side of the operating element 20(internal space side of the housing 12) for preventing detachment of thelocking ring 72.

What is claimed is:
 1. A disposable lancing device comprising: ahousing; a spring member; a lancet having a puncture member provided ata distal end thereof, the lancet being housed in the housing and urgedby the spring member such that the puncture member is configured toextend out from the housing and carry out a puncturing operation; alocking ring disposed within the housing such that the lancet is allowedto displace in an extension direction through the locking ring; alocking protrusion extending from the lancet and adapted to be engagedby the locking ring so as to hold the lancet in a puncture-readyposition located deep in the housing with the spring member beingcompressed; an operating member adapted to carry out the puncturingoperation by rotating the locking ring so as to disengage the lockingprotrusion from the locking ring and displace the lancet in theextension direction by means of the spring member; and areuse-preventing protrusion provided on the lancet and configured toprevent the locking protrusion from being re-engaged by the locking ringsuch that with the locking ring located at a rotational positionrepresenting that the locking protrusion has been disengaged and thepuncturing operation of the lancet has been carried out, as the lancetis pushed and displaced deep into the housing the reuse-preventingprotrusion comes into abutment against the locking ring so as to limitdeep displacement of the lancet relative to the locking ring, whereinthe locking protrusion and the reuse-preventing protrusion are formed onan outside peripheral face of the lancet, while being spaced away fromeach other in a circumferential direction, the locking protrusion isformed at a location axially rearward by a prescribed dimension from thereuse-preventing protrusion, the locking ring is attached rotatablyabout the outside peripheral face of the lancet, and has a matingportion of an inner flange shape, the mating portion includes a firstpassage slot through which the reuse-preventing protrusion is able topass, and a second passage slot through which the locking protrusion isable to pass, and a relative position in the circumferential directionof the reuse-preventing protrusion and the locking protrusion of thelancet differs from the relative position in the circumferentialdirection of the first passage slot and the second passage slot of thelocking ring.
 2. The disposable lancing device according to claim 1,wherein subsequent to the puncturing operation, a circumferentialposition of the locking ring relative to the lancet is maintained so asto hold the locking protrusion disengaged from the locking ring so thatthe locking protrusion is prevented from being re-engaged by the lockingring.
 3. The disposable lancing device according to claim 1, wherein thelocking ring is allowed to displace deep into the housing, and with thelocking ring located at the rotational position representing that thepuncturing operation of the lancet has been carried out, as the lancetis pushed and displaced deep into the housing the reuse-preventingprotrusion comes into abutment against the locking ring so that thelocking ring experiences deep displacement together with the lancet. 4.The disposable lancing device according to claim 1, further comprisingan inadvertent operation prevention mechanism for inhibiting rotation ofthe locking ring with respect to the housing.
 5. The disposable lancingdevice according to claim 4, further comprising a cap attached to thedistal end of the lancet so as to cover the puncture member, whereinwith the cap attached, the inadvertent operation prevention mechanism isprovided by the locking ring being engaged nonrotatably with respect tothe housing via either of the cap and the lancet, and through detachmentof the cap the locking ring is adapted to be disengaged to becomerotatable.
 6. The disposable lancing device according to claim 1,further comprising a guide mechanism for guiding the lancet in theextension direction while preventing circumferential displacement of thelancet with respect to the housing.
 7. A disposable lancing devicecomprising: a housing; a spring member; a lancet having a puncturemember provided at a distal end thereof, the lancet being housed in thehousing and urged by the spring member such that the puncture member isconfigured to extend out from the housing and carry out a puncturingoperation; a locking ring disposed within the housing such that thelancet is allowed to displace in an extension direction through thelocking ring; a locking protrusion extending from the lancet and adaptedto be engaged by the locking ring so as to hold the lancet in apuncture-ready position located deep in the housing with the springmember being compressed; an operating member adapted to carry out thepuncturing operation by rotating the locking ring so as to disengage thelocking protrusion from the locking ring and displace the lancet in theextension direction by means of the spring member; a reuse-preventingprotrusion provided on the lancet and configured to prevent the lockingprotrusion from being re-engaged by the locking ring such that with thelocking ring located at a rotational position representing that thelocking protrusion has been disengaged and the puncturing operation ofthe lancet has been carried out, as the lancet is pushed and displaceddeep into the housing the reuse-preventing protrusion comes intoabutment against the locking ring so as to limit deep displacement ofthe lancet relative to the locking ring; another locking protrusion; andanother reuse-preventing protrusion, wherein the locking protrusions areformed on an outside peripheral face of the lancet and are opposed toeach other in one diametric direction of the lancet, while thereuse-preventing protrusions are formed on the outside peripheral faceof the lancet and are opposed to each other in another diametricdirection of the lancet, and the locking protrusions are formed atlocations axially rearward by a prescribed dimension from thereuse-preventing protrusions.
 8. A disposable lancing device comprising:a housing; a spring member; a lancet having a puncture member providedat a distal end thereof, the lancet being housed in the housing andurged by the spring member such that the puncture member is configuredto extend out from the housing and carry out a puncturing operation; alocking ring disposed within the housing such that the lancet is allowedto displace in an extension direction through the locking ring; alocking protrusion extending from the lancet and adapted to be engagedby the locking ring so as to hold the lancet in a puncture-readyposition located deep in the housing with the spring member beingcompressed; an operating member adapted to carry out the puncturingoperation by rotating the locking ring so as to disengage the lockingprotrusion from the locking ring and displace the lancet in theextension direction by means of the spring member; a reuse-preventingprotrusion provided on the lancet and configured to prevent the lockingprotrusion from being re-engaged by the locking ring such that with thelocking ring located at a rotational position representing that thelocking protrusion has been disengaged and the puncturing operation ofthe lancet has been carried out, as the lancet is pushed and displaceddeep into the housing the reuse-preventing protrusion comes intoabutment against the locking ring so as to limit deep displacement ofthe lancet relative to the locking ring; another locking protrusion; andanother reuse-preventing protrusion, wherein the locking ring is of acircular ring shape that is rotatably attached about the outsideperipheral face of the lancet, and has a mating portion of an innerflange shape, the mating portion including a pair of first passage slotsopposed to each other in one diametric direction of the locking ringwhile having a slightly larger cross section than the reuse-preventingprotrusions, a pair of second passage slots opposed to each other inanother diametric direction of the locking ring while having a slightlylarger cross section than the locking protrusions, and an intersectionangle formed between the one diametric direction of the pair of firstpassage slots and the another diametric direction of the pair of secondpassage slots differs from an intersection angle formed between the onediametric direction of the locking protrusions and the another diametricdirection of the reuse-preventing protrusions on the lancet.